Not all art is displayed in a museum. For example, yarn bombing or guerilla knitting grew out of a movement in Texas to use up old yarn. Today, city dwellers might walk outside to find trees, bike racks, or even mail boxes covered by intricately knitted covers. The result is colorful, fun, and easily removed. However, other street art--such as graffiti--isn't seen as so harmless. Through fact boxes and pointed questions, the main content asks readers...